1. Field of the Invention
This invention relates to an ink tank for supplying ink to an ink jet head for discharging ink to thereby effect recording, a recording head cartridge and an ink jet recording apparatus.
2. Related Background Art
An ink tank for supplying ink to a recording head for discharging ink to thereby effect recording is generally provided with an absorbing member for holding the ink therein, a tank container containing the absorbing member therein, and an atmosphere communicating port communicating the interior of the tank container with the atmosphere.
Also, a space portion (buffer portion) not including the absorbing member is provided in the tank container, and the buffer portion temporarily contain therein the ink going out of the interior of the absorbing member due to a change in the environment around the ink tank to thereby prevent the leakage of the ink from the ink tank to the outside.
As the ink absorbing member for holding the ink therein, use has heretofore been made of a foamed material typified by urethane. Also, in recent years, as a material replacing the foamed material such as urethane, there has been proposed an absorbing member using a compressed fiber-like material comprising chemically more stable polyolefin resin.
However, in the prior-art ink tank as described above, the ink going out of the absorbing member due to a change or the like in the external environment stays in the buffer portion, and when in that state, a force such as a shock is applied from outside, the ink in the buffer portion may leak to the outside.
Also, generally, the ink tank is carried on the carriage of an ink jet recording apparatus, but the carriage is reciprocally scanned and therefore, the ink moves from the interior of the absorbing member to the buffer portion by the acceleration or inertia force during that scanning, and it is also conceivable that the ink in the buffer portion further leak to the outside.
The present invention has been made in order to solve the above-noted problems peculiar to the prior art and the object thereof is to provide an ink tank suppressing the leakage of ink to the outside, a recording head cartridge in which the ink tank is mounted, and an ink jet recording apparatus on which the recording head cartridge is carried.
To achieve the above object, the ink tank of the present invention is an ink tank having an absorbing member for holding therein ink to be supplied to a recording head for discharging ink to thereby effect recording, a tank container containing the absorbing member therein, a buffer portion capable of temporarily containing the ink therein, and an atmosphere communicating port disposed in the buffer portion and communicating the interior of the ink containing portion with the atmosphere, characterized in that the buffer portion is disposed on the side portion of the absorbing member, and the direction from the absorbing member toward the buffer portion is a direction intersecting with the scanning direction of a carriage.
Also, another form of the ink tank of the present invention is an ink tank having an absorbing member for holding therein ink to be supplied to a recording head for discharging ink to thereby effect recording, a tank container containing the absorbing member therein, a buffer portion capable of temporarily containing the ink therein, and an atmosphere communicating port disposed in the buffer portion and communicating the interior of the ink containing portion with the atmosphere, characterized in that the absorbing member is of a convex shape in which at least two opposed surfaces swell outwardly, and has a bottom surface buffer portion disposed between the absorbing member and the bottom surface of the ink tank and capable of temporarily containing the ink therein, and a clearance communicating the buffer portion and the bottom surface buffer portion with each other.
In the ink tank constructed as described above, the buffer portion is disposed in the direction intersecting with the scanning direction of the carriage, whereby the ink only moves in the interior of the absorbing member and is prevented from moving to the buffer portion and therefore, a change in the negative pressure in the interior of the ink tank is suppressed. Also, even if the carriage changes its scanning direction, whereby an inertia force acts on the ink in the ink tank, the ink will not directly move into the buffer portion.
Also, even when the ink flows out into the buffer portion, the ink is again taken in quickly from the side of the absorbing member and full use of the ink is achieved well because the buffer portion is located on the side portion of the ink tank.
On the other hand, the absorbing member is of a convex shape in which two opposed surfaces swell outwardly, and has a bottom surface buffer portion disposed between the absorbing member and the bottom surface of the ink tank and capable of temporarily containing the ink therein, and a clearance communicating the buffer portion and the bottom surface buffer portion with each other, whereby the ink moving from the absorbing member to the bottom surface side of the interior of the ink tank can be temporarily retracted into the bottom surface buffer portion. Further, by the bottom surface buffer portion and the buffer portion being communicated with each other by the clearance, the ink overflowing to the bottom surface buffer portion can be prevented from leaking out from the recording head by the ambient temperature rise.
The present invention also provides a recording head cartridge in which the above-described ink tank can be removably carried, and an ink jet recording apparatus.